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在北京市顺义县小麦、玉米一年二作区选取冲积平原、自然堤、洼地和洪冲积扇下部四种地貌研究无机氮在土壤剖面中的周年变化规律。研究结果认为冲积平原的砂壤土、自然堤上的砂土，土壤水份周年变化较大，而洼地的粘壤土及洪冲积扇下部的壤土土壤水份周年变化较小，地下水位较高。氨态氮在任何地貌部位都有类似的变化规律，春夏季低、秋季高。洼地土壤剖面硝态氮的含量前期上高下低，后期下高上低，这可能是ＮＯ－３淋洗的结果；其他地貌部位土壤的硝态氮含量除个别情况外，上低下高。
In the area of Shunyi County, Beijing, two alluvial plains, natural dike, depression and the lower part of flood alluvial fan were selected to study the annual variation of inorganic nitrogen in soil profiles. The results show that annual changes of sandy loam soil and natural dike on the alluvial plain are larger than that of the natural dike, while clay soil in the depression and loamy soil below the flood alluvial fan have smaller annual variations in soil moisture and higher groundwater table. Ammonia nitrogen in any landform has a similar pattern of change, low in spring and summer, autumn high. The content of nitrate nitrogen in the lowland soil profile was lower in the early stage and lower in the late stage, which may be the result of NO-3 leaching. The nitrate nitrogen content in the soil of other topographical sites was higher than that in some other situations.